Given how hard it is to determine what is actually causing high load sometimes I'm surprised we haven't evolved more easily actionable metrics.
You could poll that ever so often and log the results to a database if you actually cared; but the act of measuring changes the results...
When you're in top, what's the top process?
top!
"Hey man, good news, I've found the problem!
I'm the problem!!
Who would've thought that?!
Don't run me!"